一些代理签名方案的进一步改进

Further improvement of some proxy signature schemes

对两个不需要安全信道的代理签名方案进行了分析,发现它们并不满足不可伪造性。在[4]中不能抵抗原始签名人改变攻击,在[5]中原始签名人可以伪造一个有效的代理签名。提出一个改进的强代理签名方案,新方案在不增加计算复杂性的前提下,保证了签名的安全性,同时代理授权过程中仍然保持不需要安全信道。

This paper analyzes two public channel proxy signature schemes,we point out that both schemes are insecure;the scheme of [4] can＇t resist the change original signer attack.In the scheme of [5],original signer can successfully forge a valid proxy signature scheme.A new public channel signature scheme is proposed.Analysis shows that the proposed scheme satisfies all security properties of the strong proxy signature scheme.